selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 147 insertions, 0 deletions

diff --git a/arch/m68k/coldfire/m5249.c b/arch/m68k/coldfire/m5249.c
new file mode 100644
index 000000000..5a0495a2b
--- /dev/null
+++ b/arch/m68k/coldfire/m5249.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0
+/***************************************************************************/
+
+/*
+ *	m5249.c  -- platform support for ColdFire 5249 based boards
+ *
+ *	Copyright (C) 2002, Greg Ungerer (gerg@snapgear.com)
+ */
+
+/***************************************************************************/
+
+#include <linux/clkdev.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <asm/machdep.h>
+#include <asm/coldfire.h>
+#include <asm/mcfsim.h>
+#include <asm/mcfclk.h>
+
+/***************************************************************************/
+
+DEFINE_CLK(pll, "pll.0", MCF_CLK);
+DEFINE_CLK(sys, "sys.0", MCF_BUSCLK);
+
+struct clk_lookup m5249_clk_lookup[] = {
+	CLKDEV_INIT(NULL, "pll.0", &clk_pll),
+	CLKDEV_INIT(NULL, "sys.0", &clk_sys),
+	CLKDEV_INIT("mcftmr.0", NULL, &clk_sys),
+	CLKDEV_INIT("mcftmr.1", NULL, &clk_sys),
+	CLKDEV_INIT("mcfuart.0", NULL, &clk_sys),
+	CLKDEV_INIT("mcfuart.1", NULL, &clk_sys),
+	CLKDEV_INIT("mcfqspi.0", NULL, &clk_sys),
+	CLKDEV_INIT("imx1-i2c.0", NULL, &clk_sys),
+	CLKDEV_INIT("imx1-i2c.1", NULL, &clk_sys),
+};
+
+/***************************************************************************/
+
+#ifdef CONFIG_M5249C3
+
+static struct resource m5249_smc91x_resources[] = {
+	{
+		.start		= 0xe0000300,
+		.end		= 0xe0000300 + 0x100,
+		.flags		= IORESOURCE_MEM,
+	},
+	{
+		.start		= MCF_IRQ_GPIO6,
+		.end		= MCF_IRQ_GPIO6,
+		.flags		= IORESOURCE_IRQ,
+	},
+};
+
+static struct platform_device m5249_smc91x = {
+	.name			= "smc91x",
+	.id			= 0,
+	.num_resources		= ARRAY_SIZE(m5249_smc91x_resources),
+	.resource		= m5249_smc91x_resources,
+};
+
+#endif /* CONFIG_M5249C3 */
+
+static struct platform_device *m5249_devices[] __initdata = {
+#ifdef CONFIG_M5249C3
+	&m5249_smc91x,
+#endif
+};
+
+/***************************************************************************/
+
+static void __init m5249_qspi_init(void)
+{
+#if IS_ENABLED(CONFIG_SPI_COLDFIRE_QSPI)
+	/* QSPI irq setup */
+	mcf_write8(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL4 | MCFSIM_ICR_PRI0,
+	       MCFSIM_QSPIICR);
+	mcf_mapirq2imr(MCF_IRQ_QSPI, MCFINTC_QSPI);
+#endif /* IS_ENABLED(CONFIG_SPI_COLDFIRE_QSPI) */
+}
+
+/***************************************************************************/
+
+static void __init m5249_i2c_init(void)
+{
+#if IS_ENABLED(CONFIG_I2C_IMX)
+	u32 r;
+
+	/* first I2C controller uses regular irq setup */
+	mcf_write8(MCFSIM_ICR_AUTOVEC | MCFSIM_ICR_LEVEL5 | MCFSIM_ICR_PRI0,
+	       MCFSIM_I2CICR);
+	mcf_mapirq2imr(MCF_IRQ_I2C0, MCFINTC_I2C);
+
+	/* second I2C controller is completely different */
+	r = mcf_read32(MCFINTC2_INTPRI_REG(MCF_IRQ_I2C1));
+	r &= ~MCFINTC2_INTPRI_BITS(0xf, MCF_IRQ_I2C1);
+	r |= MCFINTC2_INTPRI_BITS(0x5, MCF_IRQ_I2C1);
+	mcf_write32(r, MCFINTC2_INTPRI_REG(MCF_IRQ_I2C1));
+#endif /* CONFIG_I2C_IMX */
+}
+
+/***************************************************************************/
+
+#ifdef CONFIG_M5249C3
+
+static void __init m5249_smc91x_init(void)
+{
+	u32  gpio;
+
+	/* Set the GPIO line as interrupt source for smc91x device */
+	gpio = mcf_read32(MCFSIM2_GPIOINTENABLE);
+	mcf_write32(gpio | 0x40, MCFSIM2_GPIOINTENABLE);
+
+	gpio = mcf_read32(MCFINTC2_INTPRI5);
+	mcf_write32(gpio | 0x04000000, MCFINTC2_INTPRI5);
+}
+
+#endif /* CONFIG_M5249C3 */
+
+/***************************************************************************/
+
+void __init config_BSP(char *commandp, int size)
+{
+	mach_sched_init = hw_timer_init;
+
+#ifdef CONFIG_M5249C3
+	m5249_smc91x_init();
+#endif
+	m5249_qspi_init();
+	m5249_i2c_init();
+
+	clkdev_add_table(m5249_clk_lookup, ARRAY_SIZE(m5249_clk_lookup));
+}
+
+/***************************************************************************/
+
+static int __init init_BSP(void)
+{
+	platform_add_devices(m5249_devices, ARRAY_SIZE(m5249_devices));
+	return 0;
+}
+
+arch_initcall(init_BSP);
+
+/***************************************************************************/